A Facile, Selective Preparation of Monoketals from Pentaerythritol and Ketones

Abstract

The selective preparation of monoketals 3a-f from pentaerythritol 1 and cyclic, acyclic, aromatic, and aliphatic ketones 2a-f was achieved by a facile method. The extreme polarity and low solubility of pentaerythritol in almost all organic solvents were the main difficulties to be overcome for the preparation of monoketals in good yields and high selectivity. A benzene-dimethylformamide (40:60) mixture proved to be excellent for the ketalization. The onestep procedure developed allowed the preparation of monoketals in good yields and good to excellent selectivity (higher than 90%).

Competitive Photoisomerization and Energy Transfer Processes in Fluorescent Multichromophoric Systems

“… [7] With the aim of gathering several independent DCM units, two dendritic linkers 2 and 3 with two and three propargyl groups respectively were firstly prepared (Scheme 1 ). Compound 2 was obtained after di‐ O ‐propargylation of isopropylidene acetal protected pentaerythritol 1 , [8] while 3 was synthesized according to the reported procedure. [9] CuAAC reaction of 2 with ( E )‐ DCM under microwave irradiation led to 2DCM as pure ( EE )‐isomer in 82 % yield, by shielding the ambient light during the whole synthesis procedures.…”